Rock cutting and excavation machines have been developed for various specific applications including mining, trenching, tunnelling, foundation drilling, road milling, etc. Typically, a drive body in the form of a rotatable drum or drill head comprises a plurality of replaceable cutting bits that provide the points of contact for the material or mineral face.
The term cutting bit typically refers to a pointed or chisel shaped cutting tool that acts to cut rock by penetrating and scraping along the rock surface. The tool, also referred to as a pick, drag-tool or cutting tool, commonly has a steel shank provided with a cutting tip that may be formed from tungsten carbide, a polycrystalline diamond composite (PDC) or silicon carbide-diamond (SCD) composite.
In one implementation, a mobile mining machine comprises a rotating cutting head with bit holders for mounting and orientating the cutting bits to strike the rock at a desired angle of attack. The cutting bits are arranged specifically on the rotating drums to work cooperatively and to follow one another to facilitate the rock fragmentation via a minimum energy input.
Many different processes and arrangements have been proposed for attachment of the super-hard diamond cutting tips to the shank of the cutting tool. As will be appreciated, the bond between the diamond composite and the tool support body is required to be sufficiently strong to withstand the significant forces transferred through the tool during the repeated and continuous cutting operations. In some instances, the tip may be bonded directly to the pick body by brazing or soldering. WO 93/25795; WO 01/88322; US 2006/0272790 and WO 2011/089117 disclose cutting tools in which a diamond composite tip is bonded to a support body by brazing. An alternative bonding method is described in GB 2493282 in which the PCD composite tip is fused to a support structure by pressing the two components together at ultra-high pressure and temperature.
However, conventional arrangements and assembly methods are not optimised to allow a cutting tool to be manufactured conveniently, efficiently and economically whilst providing a tool that is capable of withstanding the significant loading and stress forces during cutting so as to ensure the cutting tip is not dislodged from the tip holder.